Studies on the influence of physical and chemical factors on the activity of chitinases produced by planktonic bacteria isolated from the lake Jeziorak were carried out. The results evidenced maximum activity of bacterial strains at pH 6.0 and at 10°C and 30°C. Among the strains studied, higher activity was recorded along with an increase in colloidal chitin concentration. The highest activity was recorded at 2% concentration of chitin. The majority of strains hydrolysed chitin most intensely after 192 h of incubation, whereas no strain revealed chitinases activity after 48 h.